1. Field of the Invention
The present invention relates to electronic products with a standby power source, and more particularly, to an electronic product with a standby power source which can reduce power consumption during a standby state.
2. Description of the Related Art
Generally, televisions or video cassette recorders for home use utilize a standby power source as well as a main power source according to a tendency toward multifunction and low power. Therefore, during a standby state, the main power source is turned off, and only the smallest number of circuits, for example, a microprocessor having a timer function and a memory circuit, etc., are driven by the standby power source.
FIG. 1 illustrates the construction of a conventional electronic product with such a standby power source. In a main power source circuit 1, a commercial alternating current (AC) 10 received through a power switch 12 is full-wave rectified through a first diode bridge 14, smoothed to a DC voltage through a smoothing capacitor 16, lowered through a main power transformer 18, and generated as various driving voltages necessary for an operation of a circuit through a rectifier circuit including a diode 20 and a capacitor 22. Meanwhile, in a standby power circuit 3, the commercial AC 10 is full-wave rectified through a second diode bridge 22, smoothed to a DC voltage through a smoothing capacitor 24, lowered through an auxiliary power transformer 26, and generated as a standby voltage, 6.5V for example, through a rectifier circuit including a diode 28 and a capacitor 30.
If two diode bridges are formed on the same printed circuit board 4, a ground pattern is shared. Therefore, during the standby state, although the power switch 12 is in an off state, a main power source is generated during a negative cycle of the AC by forming a current path through the first diode bridge 14, the smoothing capacitor 16, the common ground pattern and the second diode bridge 22. Consequently, unnecessary power is consumed.